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experimental new unsat core based overlap detection

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This commit is contained in:
Murphy Berzish 2017-04-12 17:09:35 -04:00
parent eef2bbadad
commit 7207cabc97
5 changed files with 82 additions and 14 deletions
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61
src/smt/smt_context.cpp
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@ -37,7 +37,7 @@ Revision History:
#include"model_pp.h"
#include"ast_smt2_pp.h"
#include"ast_translation.h"
#include"theory_str.h"
#include"theory_seq.h"
namespace smt {
@ -76,6 +76,8 @@ namespace smt {
m_unsat_proof(m),
m_unknown("unknown"),
m_unsat_core(m),
m_use_theory_str_overlap_assumption(false),
m_theoryStrOverlapAssumption_term(m_manager),
#ifdef Z3DEBUG
m_trail_enabled(true),
#endif
@ -3269,21 +3271,38 @@ namespace smt {
// PATCH for theory_str:
// UNSAT + overlapping variables => UNKNOWN
if (r == l_false) {
ptr_vector<theory>::iterator it = m_theory_set.begin();
ptr_vector<theory>::iterator end = m_theory_set.end();
for (; it != end; ++it) {
theory * th = *it;
if (strcmp(th->get_name(), "strings") == 0) {
theory_str * str = (theory_str*)th;
if (str->overlapping_variables_detected()) {
TRACE("t_str", tout << "WARNING: overlapping variables detected, UNSAT changed to UNKNOWN!" << std::endl;);
TRACE("context", tout << "WARNING: overlapping variables detected in theory_str. UNSAT changed to UNKNOWN!" << std::endl;);
r = l_undef;
}
if (r == l_false && use_theory_str_overlap_assumption()) {
// check the unsat core for an assumption from theory_str relating to overlaps.
// if we find this assumption, we have to answer UNKNOWN
// otherwise, we can pass through UNSAT
TRACE("t_str", tout << "unsat core:\n";
unsigned sz = m_unsat_core.size();
for (unsigned i = 0; i < sz; i++) {
tout << mk_pp(m_unsat_core.get(i), m_manager) << "\n";
});
bool assumptionFound = false;
unsigned sz = m_unsat_core.size();
app * target_term = to_app(m_manager.mk_not(m_theoryStrOverlapAssumption_term));
internalize_term(target_term);
for (unsigned i = 0; i < sz; ++i) {
app * core_term = to_app(m_unsat_core.get(i));
// not sure if this is the correct way to compare exprs in this context
enode * e1;
enode * e2;
e1 = get_enode(target_term);
e2 = get_enode(core_term);
if (e1 == e2) {
// found match
TRACE("t_str", tout << "overlap detected in unsat core; changing UNSAT to UNKNOWN" << std::endl;);
assumptionFound = true;
r = l_undef;
break;
}
}
if (!assumptionFound) {
TRACE("t_str", tout << "no overlaps detected in unsat core, answering UNSAT" << std::endl;);
}
}
return r;
@ -3302,6 +3321,22 @@ namespace smt {
SASSERT(m_scope_lvl == 0);
SASSERT(!m_setup.already_configured());
setup_context(m_fparams.m_auto_config);
// theory_str requires the context to be set up with a special assumption.
// we need to wait until after setup_context() to know whether this is the case
if (m_use_theory_str_overlap_assumption) {
TRACE("t_str", tout << "enabling theory_str overlap assumption" << std::endl;);
// TODO maybe refactor this a bit
symbol strOverlap("!!TheoryStrOverlapAssumption!!");
expr_ref_vector assumption(get_manager());
seq_util m_sequtil(m_manager);
sort * s = m_manager.mk_bool_sort();
m_theoryStrOverlapAssumption_term = expr_ref(m_manager.mk_const(strOverlap, s), m_manager);
assumption.push_back(m_manager.mk_not(m_theoryStrOverlapAssumption_term));
// this might work, even though we already did a bit of setup
return check(assumption.size(), assumption.c_ptr(), reset_cancel);
}
internalize_assertions();
lbool r = l_undef;
if (m_asserted_formulas.inconsistent()) {